The purpose of insulation is well known, it is to reduce the impact of ambient environmental conditions on desired temperature within the insulated environment by reducing the heat transfer driving force between the insulated and ambient environments. The insulation operation involves the location and fastening of layer(s) of insulating materials, which may be of the same or different nature, about the component to be insulated. The installation may involve wrapping of an insulating material about the component but other constructions, for example panel constructions, which are adhered or otherwise secured to the component may also be employed.
In the industrial context, the objectives of insulation of a component include maintaining a desired temperature within that component; and personnel protection. Thus in a chemical plant, tanks and pipes may hold or carry materials such as solids, gases or liquids which must be maintained within controlled temperature limits for efficient use within the process being conducted within the chemical plant.
Achievement of this objective is directly linked to the cost efficiency of the chemical plant as heating and cooling costs may be substantial and may be reduced by effective insulation to prevent heat loss or gain from the insulated component.
Insulation of a chemical plant is an expensive process. Generally, it has involved the installer in the transport of the necessary cladding and insulation materials to the site where it is then manufactured into the desired form to complete the insulation job. Therefore, the process is time consuming and requires a great deal of organisation to be competently and cost effectively carried out.
Development of suitable insulation materials for cryogenic processes poses a particular difficulty. Cryogenic plants in conventional use, for example in gas processing, operate at temperatures well below the freezing point of water. Indeed, temperatures may be −140° C. or lower. Therefore, insulation barriers in cryogenic plants are subject to high thermal shock or stress profiles making development of suitable insulators very difficult.
By way of example, the temperature difference between the interior of the insulated component and the ambient environment may be of the order of 200° C. such that expansion behaviour may be encountered in outer portions of the insulation and contraction behaviour may be encountered in inner portions of the insulation.
Still further, the insulation barrier must avoid ingress of water which, on freezing, will cause loss of insulation capability and possibly more serious problems including insulation failure. All these problems mean that specific insulation techniques and materials are required in cryogenic applications.
As with other insulation applications, major costs are encountered in the installation operation as various insulation materials must be fabricated on site to meet the requirements of the application.